Symposium EN06—Sustainable Electronics—Green Chemistry, Circular Materials, End-of-Life and Eco-Design

Driven by the rapid growth of the Internet of Things (IoT) and its role in building smart buildings and cities, sub-floor sensors based on triboelectric nanogenerators (TENGs) that are primarily composed of cellulosic materials have gained increasing attention due to the low cost, sustainability, and abundance of such materials. In this work, we developed a high output performance of a cellulosic material-based energy harvesting floor (CEHF). Benefiting from the significant difference in the triboelectric properties between weighing and nitrocellulose papers, high surface roughness achieved by a newly developed mechanical exfoliation method, and large overall contact area via a multilayered device structure, a wireless transmission sensing system is instantaneously powered by a TENG based entirely on cellulosic materials for the first time. This work provides a feasible and effective way to utilize eco-friendly cellulosic materials in constructing self-powered wireless transmission systems for future smart city.

Edible electronics is an evolving field of research whose ultimate goal is to develop a new class of microelectronic devices that are edible. The concept of this unconventional approach implies the use of natural and food-based materials, and their electronic properties for realization of safe for ingestion devices. The unique combination of electronic functionality, low cost, and safety for both human and environment suggests broad application opportunities for smart medications and food safety monitoring.
In this framework, we explore the potential of natural edible substances, honey and chitosan, to be used as electrolytic gate dielectrics in complementary organic transistors and integrated logic circuits, namely, inverting logic gates and ring oscillators. Low voltage operation in air < 1 V and compatibility with both hole and electron transporting materials are the feature characteristics of the designed devices. In addition, a strong responsivity of the devices to relative humidity levels suggests their possible use as humidity indicators, in perspective, for moisture monitoring of dried or dehydrated food. Lastly, we realize the arrays of lightweight fully printed devices on edible flexible and conformable substrates.

The growing demand of disposable electronics raises serious concerns for the corresponding increase amount of electronic waste (e-waste), with severe environmental impact. Organic and flexible electronics have been proposed long ago as a more sustainable and energy efficient technological platform with respect to established ones. Yet, such technology is inevitably leading to a drastic increase of plastic waste if common approaches for flexible substrates are followed. In this scenario, biodegradable solutions can significantly limit the environmental impact, actively contributing to eliminate the waste streams (plastic or electronic) associated with disposal of devices. However, achieving suitably scalable processes to pattern mechanically robust organic electronics onto largely available biodegradable substrates is still an open challenge. In this work, all-organic and highly flexible field-effect transistors, inkjet printed onto biodegradable and compostable substrates (such as commercial Mater-Bi and polyhydroxybutyrate - PHB - biopolymer) are demonstrated. The degradation behavior of the final system shows unaltered biodegradability level. Furthermore, the electrical characterization of the devices showed a proper current modulation, which remained almost unaltered also after intensive mechanical stresses as bending and rolling. Such mechanical stability and flexibility together with the biodegradability, make these devices great candidates for new demanding applications in the field of biomedical electronics or food packaging. These results represent a promising step toward sustainable flexible and large area electronics, combining energy and materials efficient processes with largely available biodegradable substrates.

Over the last few years, the terrific technological advancements in the field of electronics paralleled by higher purchasing power, large scale urbanization and industrialization, shorter lifetime and replacing cycles, lead to the generation of unbearable amounts of Waste Electrical and Electronics Equipment (E-Waste).^1,2 Only in 2019, 53.6 Mt of E-Waste were produced worldwide and such amount is expected to growth up to 74.7 Mt by 2030.¹ E-Waste contains toxic elements that if buried in landfill or inhaled, can seriously put in danger the health of the current and future generations.
A paradigm shift from linear to circular economy, focusing on eco-design, durability, refurbishment and recycling is needed.^3,4 A viable route to reduce the carbon footprint of electronics is the development of Sustainable Green Organic Electronics, using ubiquitous biosourced (bioinspired), biocompatible, compostable and possibly biodegradable materials.⁵ Among the biosourced matarials available in nature, eumelanin is one of the most fascinating.⁶ The synergy between electronic conjugation (alternance of single-double carbon bonds) and hydration dependent electrical response, make eumelanin a mixed protonic-electronic conductor.^7–10 Furthermore, eumelanin is a quinone-based redox active biopigment, which makes it an ideal candidate for energy storage applications.¹¹ However, the poor solubility of eumelanin in the majority of organic solvents is a real setback and often limiting its range of applications. Herein, we report on a green ink formulation method to fabricate Sepia melanin films from powders extracted from Sepia Officinalis cuttlefish ink. Our ink-formulation leads to a reproducible, effective printing of Sepia melanin on flexible substrates (i.e. polyethylene terephthalate (PET), paper) and carbon paper. Sepia ink can be also spin-coated and/or brushed on several patterned substrates. Sepia melanin films exhibit high electrical conductivity and environmental stability. Our results open the debate whether Eumelanin features exclusive electronic transport under certain conditions. Work is in progress to study structural aggregation of Sepia particles in the ink to shed light onto the efficient charge carrier transport properties herein observed.

References:

1 V. Forti, C. P. Baldé, R. Kuehr and G. Bel, The Global E-waste Monitor 2020: Quantities, Flows, and the Circular Economy Potential, 2020.
2 C. P. Balde, V. Forti, V. Gray, R. Kuehr and P. Stegmann, The Global E-waste Monitor 2017. Quantities, Flows and Resources., United Nation University, 2017.
3 H. Zhao, D. Waughray, D. M. Malone, J. Msuya, G. Ryder, P. Bakker, N. Seth, L. Yong and R. Payet, World Econ. Forum, 2019, 1–24.
4 M. Meloni, F. Souchet and D. Sturges, Ellen MacArthur Found., 2018, 1–17.
5 S. Irimia-Vladu, M., Glowacki, E. D., Sariciftci, N. S. & Bauer, Green Materials for Electronics, Wiley-VCH, Weinheim, Germany, 2018.
6 M. Reali, P. Saini and C. Santato, Mater. Adv., 2021, 2, 15–31.
7 M. Reali, A. Gouda, J. Bellemare, D. Ménard, J. M. Nunzi, F. Soavi and C. Santato, ACS Appl. Bio Mater., 2020, 3, 5244–5252.
8 A. B. Mostert, B. J. Powell, I. R. Gentle and P. Meredith, Appl. Phys. Lett, 2012, 100, 1–3.
9 M. Sheliakina, A. B. Mostert and P. Meredith, Adv. Funct. Mater., 2018, 1805514.
10 M. Reali and C. Santato, in Handbook of Nanoengineering, Quantum Science and Nanotechnology, ed. S. E. Lyshevski, CRC Press, 1st edn., 2019, pp. 101–113.
11 A. Gouda, S. R. Bobbara, M. Reali and C. Santato, J. Phys. D. Appl. Phys., 2020, 53, (4), 043003.

Smart packaging has become a multi billion-dollar industry that relies on the integration of flexible and inexpensive sensors within product packaging to provide critical quality assurance information such as temperature and humidity. However, these sensors need to be flexible, biodegradable, and low cost in order to be incorporated into a wide variety of packaging.¹
One way to address these issues is by using organic thin film transistors (OTFTs) which are fabricated using carbon-based active materials, can be integrated onto flexible substrates, and have found many sensing applications. The dielectric is one of the active layers within an OTFT. It facilitates charge accumulation at the organic semiconductor interface when a source-gate voltage is applied. The ideal dielectric should have low leakage currents and a high dielectric constant. Unfortunately, most polymer dielectrics that meet these requirements are not environmentally friendly.
Poly(vinyl alcohol) (PVA) is a biodegradable, water soluble, high-k dielectric polymer however it is moisture sensitive, has poor film forming properties with large leakage currents. Recently we found that the film forming capabilities could be improved through the addition of low weight percentages of cellulose nanocrystals which increase the viscosity of the solutions.² Building upon these findings, a thin layer of polycaprolactone (PCL) was deposited on top of our PVA dielectric to reduce the moisture sensitivity and leakage currents of PVA. PCL is a hydrophobic, biodegradable, low-K polymer with good insulating properties. The PCL layer was functionalized with toluene diisocyanate (TDI). The functionalized TDI-PCL can then be thermally cross-linked to the hydroxyl groups of PVA at the TDI-PCL/PVA interface. Crosslinking at the bilayer interface increased the thin film stability and facilitated orthogonal processing of the semiconducting layer. TDI-PCL/PVA metal-insulator-metal capacitors were fabricated and found to be highly stable, even after being exposed to 95% relative humidity, unlike pure PVA based devices. Finally, the TDI-PCL/PVA dielectric was used in the fabrication of single walled carbon nanotube top gate bottom contact OTFTs. The TDI-PCL/PVA dielectric showed greater average mobilities of 0.42 cm²/Vs compared to 0.032 cm²/Vs for PVA, a reduced average hysteresis, better output curve saturation, a negative threshold voltage shift and greater on/off ratios with a lower device variation. When compared against silicon dioxide the TDI-PCL/PVA dielectric had a six-fold decrease in operating voltage for both the output and transfer curves. These results demonstrate a novel method for incorporating a green bilayer dielectric in high performing OTFTs while mitigating challenges associated with thin film processing and moisture sensitivity.
1 Chen, S. et al. J. Food Sci. 85, 517–525 (2020)
2 Tousignant, M. N. et al. Langmuir 36, (2020)

Over the last decade, rapid progress in wearable devices including consumer electronics and healthcare monitoring devices resulted in an excessive increase in electronic waste. Hazardous content and limited recyclability of these electronic devices is a great threat to the environment. Thus, research and development on the “green” electronics with non-hazardous materials and facile, low-cost fabrication is a must. This requirement paved a way for a new emerging field; transient electronics. Transient electronics disintegrates at the end of their use or when it is required with almost zero waste. To achieve totally green electronics, rather than focusing on a single component in an electronic system, all of the components must be designed and engineered as transient. Herein, we successfully fabricated transient supercapacitors, capacitive sensors and triboelectric nanogenerators by engineering PVA based layers including the electrodes, electrolyte, insulating layer and the encapsulant. Fabricated supercapacitors achieved a specific capacitance of 1.8 F.g^-1 with excellent rate capability up to 1 V.s^-1. Capacitive sensors based on PVA showed a promising sensitivity of 0.49 kPa^-1 up to 44 kPa. These flexible and transient capacitive sensors were used to monitor both small and large movements in different muscle groups on human body. Fabricated single electrode triboelectric nanogenerators, on the other hand, showed an open circuit voltage and short circuit current of 18 V and 3.5 µA, respectively, charged up small sized capacitors and used as self-powered sensors.

Organic semiconductors have potential applications in various low cost, large area, flexible, light-weight devices ranging from sensors, light-emitting diodes (LEDs), displays, transistors, solar cells, photodetectors, thermoelectrics, and ratchets. Most organic semiconductors are processed in chlorinated solvents such as chlorobenzene and chloroform. In this talk, I will discuss the design, synthesis, and applications of conjugated polyelectrolytes (CPEs), a class of organic semiconductors characterized by a conjugated backbone and pendant ionic side chains. The conjugated backbone endows CPEs with the optical and charge transport properties of organic semiconductors, while the ionic functionalities render CPEs soluble in high dielectric constant media and in particular water. CPEs have been used as charge transporting layers in OLEDs, organic solar cells, perovskite solar cells, thermoelectrics, and organic electrochemical transistors.

Ingestible electronics was introduced as a powerful tool to control physiological parameters and deliver drugs with tunable rates and in a specific intestinal tract but is limited by the use of standard rigid electronics components, the risk of retention after ingestion, and the need to collect the device after expulsion, which is made of non-degradable and long-lasting materials.^[1,2,3] Edible electronics, which bridge ingestible with green electronics, propose to shift from ingestible to digestible components, ensuring a safe administration without medical supervision and enabling the degradation of the device in the body/environment after performing a specific function.^[2,3]
Producing edible electrical conductors with green methods, degradable and conformable materials, and industrially compatible processes will enable passive eatable electronics components if coupled with already abundant edible dielectrics. Such electrodes will also permit the monitoring of the maturation of vegetables through degradable and edible devices that can measure the electrical impedance of fruits, which is currently performed via Ag/AgCl electrodes.^[4] Indeed, state-of-the-art ingestible/edible conductors are rigid metals that are not safely eatable at high amounts (g/Kg), have a high price, and are not degradable in the body/environments after performing their function.^[3]
We present conductive pastes made entirely of food-grade materials with a high tolerable upper intake limit (g/Kg). A matrix made with biodegradable and digestible polymers and a micrometric size eatable conductive filler constitutes the conductors. The composite pastes are the first designed specifically for edible and sustainable electronics. These conductors can reach a resistivity in the order of 100 Ω cm, are fabricated without solvents' employment, and with processes that involve a low temperature (100°C) therefore using a small amount of energy. They exhibit tunable electromechanical features and adhesion depending on the composition. The composites are compatible with green and large-scale production processes such as extrusion, direct ink writing, and injection molding and thus are ideal for an industrial scale-up. Moreover, they feature antibacterial and hydrophobic properties, avoiding food contamination and possible adverse effect upon ingestion and the variation of their properties interacting with the body/environment.
The edible conductors are assembled as a food label that can monitor the maturation of fruit through simple electrical impedance measurements.^[4] The device can monitor the impedance change on different fruits for 14 days showing reliable results compared with standard Ag electrodes used for food monitoring. ^[4] Such technology could constitute the first building block towards green and sustainable substitutes of current ingestible conductors and the monitoring of the fruit production chain from the three to the table.
References:
[1] An ingestible bacterial-electronic system to monitor gastrointestinal health, Mimee M. et al., 2018, Science, DOI: 10.1126/science.aas9315
[2] Tattoo-Paper Transfer as a Versatile Platform for All-Printed Organic Edible Electronics, Bonacchini G. E. et al., 2018, DOI: https://doi.org/10.1002/adma.201706091
[3] Edible Electronics: The Vision and the Challenge, Sharova A.S. et al., 2021, Adv. Mater. Technol., DOI: 10.1002/admt.202000757
[4] Bio-impedance and circuit parameters: An analysis for tracking fruit ripening, Ibba P. et al., 2020, Postharvest Biol. Technol., https://doi.org/10.1016/j.postharvbio.2019.110978

Biocompatible and biodegradable devices for modulation of cells and tissues have many potential impacts on medical and industrial technologies. In this talk, I will present several recent projects in this area. First, I will discuss a bottom-up synthesis to construct a soil-like material consisting of nanostructured minerals, starch granules, and liquid metals, to mimic immobile inorganic and organic materials and the mobile phases in soil. The soil-like material is biocompatible and recyclable. It possesses chemical, optical, or mechanical responsiveness to yield write-erase electrical functions. We show this soil-like material can enhance microbial metabolism and biofuel production in vitro. It can also enrich gut bacteria diversity under a pathological condition and rectify bacterial dysbiosis in vivo. Next, I will showcase a class of granules-enabled hydrogel composites, with multiple naturally occurring biopolymers and synthetic hydrogels as the key components. The composites have many tissue-like properties, such as strain-stiffening behaviors. The granules-enabled tissue-like materials have enabled the pneumatically actuated bioelectronic devices for applications such as recording the heart electrocardiogram signal ex vivo. Moreover, I will present a newly developed nanoporous/non-porous heterojunction for improved biointerfaces. Without any interconnects or metal modifications, the heterojunction enables efficient non-genetic pulse stimulation of isolated rat hearts ex vivo and sciatic nerves in vivo with radiant exposure similar to that used in optogenetics. At the end of my talk, I will discuss future composite or heterojunction development towards more efficient biological modulation.

The increase in the share of renewable energies is essential to move towards the sustainable economy. In 2020, the share of energy from renewable sources in gross final energy consumption reached 20% in the EU, while at least 32% is targeted by 2030. In this strategic vision, the European Commission intends to highlight the advantages of biofuels in terms of reducing emissions of greenhouse gases. Accordingly, new advanced biofuels are needed and should be sustainably produced from biomass and bio-feedstock. Reforming of methane is one of the potential routes to achieve this Transition. Nevertheless, it suffers from the lack of robust catalysts to take off the ground. Dry reforming of methane (DRM) converts methane (CH4) and carbon dioxide (CO2) into syngas (CO, H2), that can be directly used or further converted into green hydrogen and/or olefins, alcohols, and other hydrocarbons. An energetic optimization of this process is possible, by considering complementary oxidant agents, such as H2O and O2. In this regards, two other reforming routes named Steam (SRM) and Bireforming (BRM) have been considered. SRM consists of the conversion of methane in the presence of steam whilst BRM transforms a mixture of CH4, CO2 and H2O into syngas. This process is one that allows the direct valorization of biogas (CH4 and CO2) for instance. Then, the syngas can be further converted into higher rate hydrogen and/or valuable chemicals via Fischer-Tropsch (FT) synthesis.
The reforming reactions require noble-supported catalysts with SiO2, Al2O3, CeO2 and ZrO2 as most common support materials and metals (Ni, Fe, Ru, Pd, …) as active phases. We have developed a new approach of catalysts for the reforming of methane, that overcome the main hurdles in the field namely (1) deactivation, (2) metal sintering, (3) coke deposition, (4) lack of robustness to the variation of feedstock composition resulting in the decrease of the efficiency. The catalysts we have developed are free of rare and noble metals and made of Hydroxyapatite, Ca10(PO4)6(OH)2 as support material, and Ni and or Co as active phases. Hydroxyapatite is a hierarchical structure with tunable physicochemical, mechanical, and thermal properties. The phosphate (PO4) utilized has been recycled from used Lithium-ion batteries. The results obtained show highest performance in hydrogen production from DRM, BRM and SRM, and in hydrocarbons production in FT reaction. This lecture will summarize the research carried out and the main findings in this field, towards the sustainable use and recycling of critical chemical elements from batteries for energy and biofuel production.

As the demand for high-performance and safe batteries increases, researchers anticipate that all-solid-state batteries are the key to satisfy the market’s needs. As large-scale production becomes possible, the unprecedented number of spent batteries will trigger disposal issues. Unfortunately, little effort is placed in recycling solid-state electrolytes. Recycling composite electrolytes is in particular complicated due to the differences in the chemical and thermal stability of each component. Herein, we propose a sustainable recycling technology, cold-sintering process, to recycle composite electrolytes, Li_6.95Mg_0.15La_2.75Sr_0.25Zr₂O₁₂ with polypropylene carbonate and lithium perchlorate (LLZO–PPC–LiClO₄), and Li_1+x+yAl_xTi_2−xSi_yP_3−yO₁₂ with bis(trifluoromethanesulfonyl)imide salts (LATP–LiTFSI). Due to the low sintering temperature, cold-sintering process can repair mechanical defects by reintegrating ceramic, polymer, and salt materials without significantly compromising their properties. LLZO–PPC–LiClO₄ and LATP–LiTFSI demonstrate extraordinary recyclability. As reprocessed samples show a similar compactness as the pristine samples and ionic conductivities are above 10⁻⁴ S cm⁻¹ at room temperature after four-times recycling. The recycled LATP–LiTFSI is electrochemically stable in lithium titanate symmetric cells over 1300 h at 0.1 mAh cm⁻². This work demonstrates the first sustainable way to recycle solid-state composite electrolytes in order to move towards a circular economy.

Lithium-ion batteries (LIBs) have emerged as the battery of choice for rapidly growing markets in electric vehicles (EVs) and grid electricity storage. This spurs a great demand for lithium, graphite, cobalt, and nickel that could outstrip the supply of virgin materials. Thus, there is an enormous interest in the development of new sustainable technologies for recycling and recovery of valuable materials from secondary resources, especially from used lithium-ion batteries. Compared to conventional high temperature pyrometallurgical or hydrometallurgical methods, the direct recycling of LIBs is a promising method because it can directly regenerate the cathode materials by relithiation without destroying the compounds. Additionally, direct recycling is a comparatively low-cost and less resource intensive method of recovering LIB materials.

However, complete regenerating the full capacity and long-term performance is still particularly challenging. For instance, the cathode materials are often coated with a nanometer-thick protecting layer, which is engineered to reduce the degrading effect on the cathode due to the direct contract with the electrolyte. The long-term charge-discharge cycling causes damage to the coating layer and it thus needs to be repaired in order to recover the material performance. To address this challenge, we have developed a novel process that can regenerate and upgrade cathode materials from aged lithium-ion batteries, as well as creating a new coating layer to improve the cathode materials’ performance. In this presentation, we will provide a case study to show the performance improvement of recycled lithium cobalt oxide (LCO) materials by forming an alumina coating layer on the surface. By controlling the thickness and sintering temperature, this surface alumina coating can be an effective way to improve the stability and cyclability of recycled LCO cathode materials. Material characterizations by XPS, SEM, STEM, and XRD help to reveal the structure and composition of the surface Al coating layer, and provides insights of the healing and protective roles of this layer for recycled LCO particles.

Recovery of non-leaching gold from e-waste gold coatings was achieved using aqueous chemistry with hydrogen peroxide and friendly organic acids that are food chain byproducts. The oxidation of the base metals, also part of the edges, enables the release of gold in its original metallic state in the form of flakes subsequently separated via simple filtration. Our route avoids crushing and chemical refining steps, reduces the losses of gold, thus saving cost and time, and decreases environmental pollution. Moreover, recovered gold, characterized by scanning electron microscopy and X-ray photoelectron spectroscopy to gain insight into the structure of the flakes and their chemical composition, was used to fabricate organic field-effect transistors making use of photolithographically patterned electrodes made of the recycled gold.

As renewables become an increasing percentage of the global energy portfolio, finding and implementing cost-effective, environmentally friendly, and sustainable grid-scale electrical energy storage devices to maintain a continuous and reliable power supply will be critical. From this perspective, hybrid supercapacitors represent an attractive alternative to batteries, being typically fabricated from more environmentally benign and easily sourced materials coupled with a cycling lifetime that often exceeds batteries by several orders of magnitude. The performance of these devices is ultimately tied to the choice of electrode material, with carbon nanotube (CNT) - manganese dioxide (MnO₂) composites receiving focus recently due to the promise of energy storage approaching that of conventional batteries. MnO₂ is an ideal material from an environmental and sustainability standpoint due to its natural abundance, low toxicity, and simple synthesis routes; however, CNT synthesis typically requires hydrocarbons as feedstock and present potential health risks via inhalation and dermal contact. Biochar, on the other hand, represents a sustainable alternative to CNT with lower predicted health risks. The fabrication of biochar is carbon negative, and significant opportunities exist to engineer the morphology through rational choice of biomass precursor. In this study, biochar-MnO₂ composites were investigated to assess their potential in hybrid supercapacitors. Biochar was obtained from a variety of commercial sources and the initial concentrations varied to synthesize a range of composites via a hydrothermal method. The morphology and microstructure were characterized using scanning and transmission electron microscopy and x-ray diffraction. Supercapacitive performances were investigated using cyclic voltammetry, charge-discharge, and rate capability studies. The resulting characterization and performance data of biochar-MnO₂ will be presented and compared to CNT-MnO₂ of identical weight composition.

Due to the continuous depletion of the fossil fuels, scientists are looking for alternative energy sources and energy storage devices. Supercapacitors are energy storage devices with higher power density and high energy density than conventional capacitors. Manganese oxides have attracted a lot of attention because of their easy preparation, environmental friendliness, and relatively low cost. However, MnO₂ suffers from low electronic conductivity, which severely limits its fast charge/discharge behavior. This can be overcome by mixing it with electronically conductive materials such as carbon black or carbon nanotubes (CNTs). Composites of MnO₂/ MWCNT were prepared using different weight ratios of MWCNTs:KMnO₄ (1:2, 1:5, 1:10, 1:15, 1:20, 1:25). The synthesized materials were physically characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM studies confirm that MnO₂ is homogeneously entangled with MWCNT. The electrochemical performances evaluation was carried out in a 3-electrode system using MnO₂/ MWCNT electrode coated onto Ni mesh as working electrode, Pt foil as counter electrode and Ag/AgCl as reference electrode. An aqueous solution of 1 M Na₂SO₄ was used as electrolyte. The specific capacitance was obtained from charge discharge studies at various current densities between 0.5 A/g – 5 A/g. The specific capacitance of MWCNTs-KMnO₄ (1:10, 1:15, 1:25) samples were obtained as 111 F/g, 159 F/g, and 161 F/g, respectively at a current density of 1 A/g. The detailed morphological and electrochemical results will be presented.

In nature, light is captured by different classes of membrane protein-pigment complexes. Two proteins of interest are retinal-containing proteins (RMP) and chlorophyll-pigment protein complexes (CPP) associated with photosynthesis. Bacteriorhodopsin (BR) is an example of an RMP that functions as a light-driven proton pump. Photosystem I (PSI) is one of two CPP associated with oxygenic photosynthesis that catalyzes photoactivated unidirectional electron transfer. Interestingly, although these proteins come from highly divergent prokaryotes, bR from archaebacteria, and PSI from cyanobacteria, they form trimeric complexes that are highly thermostable, and both are exceptionally well characterized at the structural, functional, and spectroscopic level. Both complexes have been integrated into new eco-centric, photovoltaic (PV) devices built from flexible, biodegradable, renewable carbon materials. More importantly, PSI and bR stand out as some of the best performing natural light absorbers in the bio-PV devices reported. The best power conversion efficiencies have been obtained in bio-sensitized solar cell architecture, using nanostructured wide-bandgap semiconducting electrodes to assemble these proteins. The membrane protein-pigment complexes in these devices can directly donate either electron or protons upon light absorption, enabling photo-catalyzed hydrogen production, electric power generation, chemical catalysis, and other redox reactions. Despite the progress in these bR- and PSI-sensitized solar cells, little attention has been devoted to the development of alternative counter electrodes and electrolytes to the commonly used Pt and I^-/I₃^-. A careful selection of the redox mediator and the electrolyte and counter electrode components is a core part of the design of low resistance, high photocurrent protein bio-PV devices. This work explores using a counter electrode of poly (3,4-ethylene dioxythiophene) (PEDOT) modified with carbon nanotubes for both PSI and bR devices. We also explore using hydroquinone/benzoquinone and aqueous-soluble bipyridine cobalt(II/III) complexes as direct redox mediators. It is a novel discovery that the same counter electrode and redox mediator system can perform well for two different biomolecules that have developed independently over millions of years to harvest solar energy in nature. Such compatibility of PSI and bR with a common mediator and counter electrode may be helpful to realize the uptake of a larger portion of the sun spectrum with these two natural light absorbers that have complementary absorption spectra. The improvement of bio-PVs design is an advancement towards more energy-efficient and green chemistry principles-based manufacturing paradigms as the biosynthesis of biomolecules like bR and PSI for PV feedstock contributes to CO₂ fixation from the atmosphere and solar energy is used multiple times across fabrication and device use.

Supercapacitors have been the key target as energy storage devices for modern technology that need fast charging. Although supercapacitors have large power density, modifications should be done to manufacture electrodes with high energy density, longer stability, and simple device structure. The polymorph MoS₂ has been one of the targeted materials for supercapacitor electrodes. However, it was hard to tune its phase and stability to achieve the maximum possible efficiency. Herein, we demonstrate the effect of the three main phases of MoS₂ (the stable semiconductor 2H, the metastable semiconductor 3R, and the metastable metallic 1T) on the capacitance performance. The effect of the cation intercalation on the capacitance performance was also studied in Li₂SO₄, Na₂SO₄, and K₂SO₄ electrolytes. The performance of the electrode containing the metallic 1T outperforms those of the 2H and 3R phases in all electrolytes, with the order 1T > 3R > 2H. The 1T/2H phase showed a maximum performance in the K₂SO₄ electrolyte with a specific capacitance of 590 F g^–1 at a scan rate of 5 mV s^–1. MoS₂ showed a good performance in both positive and negative potential windows allowing the fabrication of symmetric supercapacitor devices. The 1T MoS₂ symmetric device showed a power density of 225 W/kg with an energy density of 4.19 Wh/kg. The capacitance retention was 82% after 1000 cycles, which is an outstanding performance for the metastable 1T-containing electrode.

The charge transfer and transport properties of bio-sourced materials are complex, due to their chemical and structural composition. Their biosynthesis generates chemical heterogeneity, e.g. macromolecules resulting from more than one building block (monomer), and physical disorder, e.g. π-π stacked regions coexisting in the supramolecular structure. Chemical and physical disorder are key factors limiting the performance of organic electronics^1–3. Among the plethora biomaterials available in nature, eumelanin, a black-brown bio-pigment of the melanin family, is an interesting candidate for study^4–6. It is a redox-active^7–10 quinone-based bio-macromolecule featuring electronic conjugation (alternating single and double Carbon bonds bonds), broadband UV-Vis absorption and hydration-dependent electrical response^11–16. Eumelanin originates from the oxidative polymerization of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) monomers (building blocks). DHI and DHICA have several polymerization sites and co-exist in different redox states (fully reduced hydroquinone, semi-reduced semiquinone, and fully oxidized quinone). Therefore, eumelanin features chemical heterogeneity^17–19. Monomers and oligomers generate several supramolecular structures, such that eumelanin also features physical disorder²⁰. Recently, we showed that the early stages of DHI and DHICA films formation is driven by both chemical (covalent) and physical (self-assembly) interactions²¹. Particularly, self assembly of DHI is expected to deliver films featuring higher degree of pi-pi stacking with respect to DHICA, this last being a critical condition to the rational design of eumelanin-based functional devices²².
Herein, we investigate the role of oligomeric composition, relative humidity and type of solvent during DHI film processing. Preliminary results show that DHI films undergo to de-wetting^23,24 or diffusion limited aggregation (DLA) phenomena^25,26 depending on specific combination of solvent, relative humidity and molar mass distribution. Our investigation is a step forward to establish a phase diagram correlating film processing and structural properties of eumelanin films.

References
1 R. Mukherjee et al.,Soft Matter, 2015, 11, 8717–8740.
2 S. Irimia-Vladu et al.,Green Materials for Electronics, Wiley-VCH, Germany, 2018.
3 S. Riera-Galindo et al.,ACS Omega, 2018,3, 2329–2339.
4 M. D’Ischia et al., Angew. Chemie - Int. Ed., 2009, 48, 3914–3921.
5 G. Prota,Pigment Cell Res., 2000, 13, 283–293.
6 P. Meredith et al.,Pigment Cell Res., 2006, 19, 572–594.
7 Y. J. Kim et al. Proc. Natl. Acad. Sci., 2013, 110, 20912–20917.
8 R. Xu et al. ACS Omega, 2019, 4, 12244–12251.
9 A. B. Mostert et al.,Sci. Adv., 2018, 4, 1–6.
10 A. Gouda et al., J. Phys. D. Appl. Phys., 2020, 53, 043003.
11 M. Ambrico et al.,Org. Electron., 2010, 11, 1809–1814.
12 M. Sheliakina et al.,Mater. Horizons, 2018, 5, 256–263.
13 M. Sheliakina et al.,Adv. Funct. Mater., 2018, 1805514.
14 A. B. Mostert et al.,Appl. Phys. Lett, 2012, 100, 1–3.
15 M. Reali et al.,Handbook of Nanoengineering, Quantum Science and Nanotechnology, ed. S. E. Lyshevski, CRC Press, 2019,101–113.
16 M. Reali, et al., Mater. Adv., 2021, 2, 15–31.
17 S. Meng et al., Biophys. J., 2008, 94, 2095–2105.
18 M. Arzillo et al., Biomacromolecules, 2012, 13, 2379–2390.
19 A. Antidormi et al., J. Phys. Chem. C, 2018, 122, 28368–28374.
20 C. T. Chen et al., Nat. Commun., 2014, 5, 1–10.
21 M. Reali et al., J. Phys. Chem. C, 2021, 125, 3567–3576.
22 M. d’Ischia et al., Angew. Chemie - Int. Ed., 2019, 11196–11205.
23 S. A. Burke et al., J. Phys. Condens. Matter, 2009, 42, 1-14.
24 L. Xue et al., Sci., 2012, 57, 947–979.
25 J. S. Huang et al, J. Chem. Phys., 1989, 90, 25–29.
26 T. C. Halsey, Phys. Today, 2000, 53, 36–41.

Lithium-ion batteries (LIBs) have emerged as the battery of choice for rapidly growing markets in electric vehicles (EVs) and grid electricity storage. This spurs a great demand for lithium, graphite, cobalt, and nickel that could outstrip the supply of virgin materials. Thus, there is an enormous interest in the development of new sustainable technologies for recycling and recovery of valuable materials from secondary resources, especially from used lithium-ion batteries. Compared to conventional high temperature pyrometallurgical or hydrometallurgical methods, the direct recycling of LIBs is a promising method because it can directly regenerate the cathode materials by relithiation without destroying the compounds. Additionally, direct recycling is a comparatively low-cost and less resource intensive method of recovering LIB materials. However, since the aged materials are usually 5 to 10 years older than the current materials, the regenerated materials may not meet new market needs due to due to due to improvements in material properties and emerging new chemistries. In order to meet this challenge, we have developed a novel gas-phase process that can regenerate and upgrade cathode materials from aged lithium-ion batteries, as well as adding new functionality to improve the cathode materials performance. In this presentation, we will provide a case study to show the upgrading of old chemistries of cathode materials (e.g., NCM 111 and NCM 523) to newer chemistries (NCM 622 and NCM 811) After upgrading, the performance and long-term cycle performance of the high-nickel NCM cathode material are comparable to those of commercial battery materials.

This new direct battery recycling technology has the potential to create a new lithium-ion battery cathode material manufacturing process from recycled batteries as it offers systematic advantages in costs, energy efficiency, and environmental protection by reusing, recycling, and reproducing lithium-ion batteries within an optimized system.

Several studies have emerged that seek to solve the energy deficit that we face as a society, where energy storage plays an important role. In this regard, Ion-Sodium batteries (Ion-Na) represent an excellent alternative to the Ion-Li batteries currently on the market. These new Ion-Na batteries have adequate charge densities and at a lower cost. Taking this issue into account, there is great interest in studying the composition, structure, and morphology of cathodes as active materials to optimize this type of battery. [i],[ii].

In this study, the synthesis and characterization of sodium rhodizonate nanostructures to be used as cathode material in Sodium-ion batteries was carried out. In a first stage, a two-level factorial design was used as an exploratory stage to evaluate the statistical significance of the variables involved in the synthesis: i) temperature, ii) reaction time, iii) molar ratio of precursors and iv) addition time. The nanostructuring of the sodium rhodizonate crystals was carried out by the ultrasonic crystallization method and was characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The electrochemical characterization was performed using cyclic voltammetry, galvanostatic charge/discharge profiles, and cyclability. The results show that the nanostructuring of the material causes an increase in the storage capacity of sodium ions in the sodiation/desodiation process. This shows a strong size-dependence in the Na + ion intercalation process. Finally, these results will allow the generation of causal relationships that lead to the optimization of the electronic properties of alternative Na-ion batteries.


[i] Minah Lee, Jihyun Hong, Jeffrey Lopez, Yongming Sun, Dawei Feng, Kipil Lim, William C. Chueh, Michael F. Toney, Yi Cui & Zhenan Bao. Nature Energy, volume 2, pages 861–868 (2017).

[ii] R.-E. Dinnebier, H. Nuss, M. Jansen, Disodium rhodizonate: a powder diffraction study, Acta Crystallographica E61 (2005) m2148–m2150.

Transient electronics refer to emerging types that only last limited periods of time and disappear after completing their functions and generating environmentally-friendly by-products. Among many approaches that have been developed for fabricating transient circuits, printing techniques are suitable methods for mass fabricating large-area transient circuits in high printing speed. However, inks and pastes as well as the processing methods of the printed patterns remain to be developed for high-performance transient circuits with excellent electrical conductivities and mechanical robustness. This presentation will focus on our recent effort in developing transient circuits based on bioresorbable zinc nanocomposites printed on bioresorbable substrates and sintered through low-cost and high-efficient water sintering. The entire printing and sintering processes can be conducted at room temperature and in atmosphere conditions, leading to the maximum conductivity of 307664.4 S/m and the capability to withstand repeated bending for more than 8000 times. The techniques have led to the development of dissolvable consumer electronics that have the same functions as conventional devices but dissolute in the liquid environment to facilitate recycling. The materials and techniques developed in these works may reform the electronics recycling industry by reducing the cost of recycling and minimizing environmental pollution.

Melanins are ubiquitous biopigments responsible of manifold functionalities in living organisms¹. Eumelanin is a hygroscopic, black-brown biomacromolecule belonging to the family of melanin biopigments. Eumelanin originates from the oxidative polymerization of (5,6)-dihydroxindole (DHI) and (5,6)-dihydroxindole 2-carboxyl acid (DHICA) building blocks. Different available polymerization sites and co-existing redox states, as well as distinct supramolecular arrangements, bring chemical and physical disorder to the biopigment². Eumelanin features fascinating physicochemical properties such as broadband optical absorption, free radical scavenging, metal-ion chelation and hydration dependent electrical response^3,4, this last mainly attributed to protonic transport. Being non-toxic, abundant, solution processable and potentially biodegradable⁵, eumelanin is a promising candidate for green electronics⁶.
Owing to its complex structural organization, the charge carrier transport properties of eumelanin, are still elusive^7–11. Our observations of exclusive electronic transport in dry eumelanin pellets¹² reopen the debate whether the biopigment would be a mixed protonic-electronic conductor in the hydrated state and an amorphous semiconductor in the dry state¹³. Correlating supramolecular self-assembly to fundamental optical and electrical properties of eumelanin is paramount to fill such a knowledge gap.
Herein¹⁴, we investigated the early stages of formation of DHI and DHICA films at technologically relevant surfaces. We observe that the monomers aggregate, possibly eventually polymerizing in a time scale of few hours at ambient condition. Atomic Force Microscopy (AFM) images of DHI and DHICA acquired at ambient conditions (AC) show the formation of well-defined fern-like structures and regular rod-shaped structures, respectively. We attribute the growth of fern-like and rod-shaped structures to diffusion limited aggregation (DLA) and Ostwald ripening processes, respectively.
The increase of UV-Vis absorbance overtime for AC-DHI and AC-DHICA films suggests an improved -electron delocalization of oligomeric structures.
Fourier Transform Infrared (FTIR) and UV-Vis spectroscopy suggests that the interplay between chemical (oxidative polymerization) and physical interactions (hierarchical self-assembly) plays a key role during the early stages of film formation over time. Preliminary investigation into the electrical response of eumelanin films were also conducted.
Our results add a piece of knowledge to unravel structure-properties relationship in eumelanin, a condition sine qua non to design and develop eumelanin-based functional devices.

REFERENCES

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The growth of consumer electronics has drastically changed our daily routine. For instance, those electronic products (cellphone, laptop, camera, etc.) have become essential tools in our modern reality to facilitate access to information or to maintain our social activities. However, even though new performing technologies (OLED or OPV) have now emerged, the fact remains that their lifespan is limited and the resources utilized for their manufacture are demanding on the environment.

Therefore, a change in the way we harness resources and manage electronic waste is required to minimize negative impacts on the environment. Organic electronic represent a promising alternative to the traditional inorganic electronic as it is carbon-based, printable and the optoelectronic properties can be easily tuned to match the requirements. Hence, in order to eliminate electronic waste, materials from renewable and recyclable sources are sought. In this regard, forest biomass is considered the only sustainable source of organic carbon and therefore the ideal replacement for petroleum products for the production of chemical compounds. One of the resources derived from biomass, lignocellulose, is the most abundant bio-based material on earth. Indeed, the main added-value compound obtained from the depolymerization of lignin is vanillin. Vanillin is an aromatic compound with three functional groups that can be chemically modified. The present work describes how the vanillin moiety can be expanded into several building blocks for the preparation of bio-based conjugated polymers. Moreover, our synthetic approach involved direct heteroarylation polymerization (DHAP), which avoids the generation of toxic side products usually present in the preparation of conducting polymers. At last, the optoelectronics properties of the materials and their corresponding devices' performances will be discussed.

Plastic waste constitutes nearly 20% of the global e-waste worldwide. Plastic in electronics compounds the massive problem of e-waste as it cannot be recovered or separated from metallic components without laborious, energy-consuming and often noxious processes like immerising them in boiling acidic or alkaline solutions for hours. At the same time, the safe and efficient recovery of valuable metallic components from e-waste does and can provide sustainable livelihoods and create new green industries worldwide.
Smart or Stimuli-responsive polymers are so-called for their ability to undergo a reversible phase change in response to an external trigger.
These smart polymers have the potential to literally drive the circular economy by creating materials that can be endlessly recovered, reused or repurposed via a low-energy phase transition that allows it to switch between states indefinitely.
Bioastra Technologies has developed and commercialised three distinct smart polymers - a self-heaing thermoplastic skin for surgical suture training, a thermosofterning/shrinking polymer for an antibacterial implant and finally, a pH-sensitive polymer as a reversible paper cup liner.
These three polymers have been adapted and tested for its potential as an a sequestrable, recyclable and biodegradable alternative to commercial PCBs.
This presentation will cover the making of films with the electrical and mechanical properties of standard PCBS. We will demonstrate both their ability to embed basic circuitry but also use the critical phase transitions to easily separate the plastic substrate from the electronics and recycle it back to films for the same purpose or remold for alternative applications.
We will also demonstrate the compostability of the thermosensitive-responsive and pH-responsive polymer at the end of its life.
We will also discuss commercial and scale-up challenges and possible pathways to industry-wide adoption.

Modern our society has been developed with various Advanced Materials. Most of advanced materials, Metallurgical materials, Semiconductors, Ceramic materials and Plastics have been used in wide area of applications like structural, mechanical, chemical, electrical, electronic, optical, photonic, biological, medical, etc. Most of them except for bio-polymers & bio-minerals have never been produced via biological systems & processes. Thus they have been fabricated artificially and/or industrially by so-called High-Technology, where using Sophisticated Equipment & High Energetic Conditions:high temperature, high pressure, vacuum, molecule, atom, ion, plasma, etc. for their fabrications, then consumed huge amounts of resources and energies thus exhausted huge amounts of wastes: Materials, Heats and Entropy. To save this tragedy, we must consider Cascade use of Heats, and (SSP) Soft, Solution Processing (=Low-Energy Production of Advanced Materials via solution-based processing). SSP is Bio-inspired process, which means that Learn from Bio-systems then Exceed them. We have challenged to fabricate those advanced inorganic materials with desired shape/size/location,etc. directly in low energetic routes using aqueous solutions since 1989 when we could fabricate BaTiO3 film on Ti substrate in a Ba(OH)2 solution by Hydrothermal Electrochemical method at low temperatures of 60-200 C. We proposed in late 90’s an innovative concept and technology, Soft Processing or Soft, Solution Processing, that aims low energetic (=environmentally friendly) fabrication of shaped, sized, located, and oriented inorganic materials in/from solutions(1,2). It can be regarded as Green processing, or Eco-processing by other groups. When we have activated/stimulated interfacial reactions locally and/or moved the reaction point dynamically, we can get patterned ceramic films directly in solution without any firing, masking nor etching: i.e. Direct Patterning of CdS, PbS and CaWO4 on papers by Ink-Jet Reaction method, furthermore, we have succeeded to fabricate BaTiO3 patterns on Ti by a laser beam scanning(3) and carbon patterns on Si by plasma using a needle electrode scanning directly in solutions. Successes in TiO2 and CeO2 patterns by Ink-Jet Deposition, where nano-particles are nucleated and grown successively on the surface of substrate thus become dense even below 300 C. Other nano-structured 2D/3D films could be prepared without firing. Soft Processing for various 2D: Graphene, MXene,MoS2 have been established including the preparation of functionalized Graphene Ink via successive processes under ambient temperature and pressure conditions.(4-6⁾
1) MRS Bulletin,25[9],Sept. 2000, special issue for Soft Processing of Advanced Inorganic Materials ,Guest Editors:M. Yoshimura and J. Livage.
2) Yoshimura, M., J. Mater. Sci.,41 [5],1299-1306 (2006), 43[7]2085-2103(2008).
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5) Sanjeeva Rao, K and Yoshimura, M et al. Adv. Funct. Mater.,25,298305(2015)
6) E. Satheeshkumar,Y. Gogotsi,M. Yoshimura,et al. Sci, Repts, 6,32049(2016), Front. Mater. 6,216(2019), Microchim. Acta, 187,33(2020)

DSSCs are promising for future photovoltaics due to their good price/performance ratio and ability to work at wider angles. In low light, long life, mechanical robustness, ability to operate at lower internal temperatures.^{1, 2} Although DSSCs coupled with a concentrator increase the power out (Pout),³ applying a concentrator increases the device temperature to limited operation lifetime and electrolyte evaporation. Therefore, a suitable cooling system is needed to prevent temperature rise in the DSSCs coupled with a concentrator. In this study, we applied an electrolyte-flowing cooling system to prevent the temperature rise of DSSCs.

Bifacial DSSCs were fabricated with FTO/TiO2/N719dye/electrolyte/Pt/FTO structure. Adjustable external concave mirror concentrators were placed at both sides of the DSSC. Z-100 Electrolytes flowed through DSSCs equipped with silicon pipes and hydraulic pumps as a cooling system. The photovoltaic performance and device temperature rise of cells under flowing continuously (FC) and flowing with a stopping period (FS) of electrolyte were compared with those of normal cells without the flowing system (NC).

The flowing electrolyte system with FC (161.7°C) and FS (167.8°C) have a lower temperature than NC (221.8°C) after 3 hours of operation. The open-circuit voltage (Voc) decreases from around 0.75 V to 0.52 (FC), 0.53 V (FS), and 0.36 V (NC) due to the effect of temperature rise. Short-circuit current (Jsc) in both flowing systems gradually is reduced due to improper transfer of electrons in the flowing electrolyte. This reduction corresponds to increases in Z1 resistance value from 9.3 Ω to 92.1 Ω (FC) and 6.5 Ω to 33.9 Ω (FS) from electrochemical impedance spectroscopy (EIS) analysis. Pout of FS and NC are almost the same, around 7.5 mW/cm² after 3 hours operation, whereas Pout of FC decreases to 1 mW/cm². In conclusion, an electrolyte-flowing cooling system with a stopping period can reduce the temperature rise and improper transfer of electrons in electrolytes caused by flow.

Yum, J., et al., Energy Environ. Sci. 4, 842–857 (2011).
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Solar power is one of the fastest growing renewable energy technologies in the world. However, dusty weather conditions pose a threat to the solar panel’s efficiency and reduce the power produced. The lack of an effective and long-term solution that successfully cleans solar panels while consuming low energy has been a challenge for the industry. Hence, the idea of a more reliable method that is more effective and cost-efficient to employ is appealing. Among the different proposed alternatives, a very promising cleaning technique involves the utilization of an Electrodynamic Screen (EDS) to actively remove the dust. The advantages of this technique include self-cleaning, high cleaning efficiency, and the eradication of manual labor, robots, and water-based cleaning techniques. An EDS consists of a transparent dielectric laminate with electrodes embedded in it. Commonly, the electrodes are arranged in a parallel configuration. In this work, we propose and analyze the employment of different electrode arrangement configurations for the EDS based on the fractal concept. This research aims to improve the EDS performance in terms of its cleaning efficiency, power consumption, and time taken. Finite element analysis results conclude that the Hilbert fractal-based electrode arrangement design performs better than the parallel design in terms of dust repulsion. Additionally, it results in low area coverage by the electrodes, ensuring an increased transparency of the EDS, hence increasing the overall irradiance absorbed by the solar panel. Specifically, as compared to the parallel design, the proposed Hilbert design reduces the power consumption and the area ratio by 25.25% and 33.83%, respectively and it also increases the maximum electric field intensity by 30%. This increase in the electric field intensity is directly associated with higher cleaning efficiency.

On the Earth's surface, the incoming radiation comprises ~5 % of ultraviolet, visible light, 43 %, and infrared light, 52%. Exposure to high-energy UV radiation can be harmful to humans, increasing the risk of skin cancers and damage to the eyes. Not only UV light, a major part of visible light is high-energy blue light (HEBL), ranging from 400-450 nm. HEBL can also have huge negative impacts on human health. It damages our eyes and can even affect mental health. In the past decade, the dramatic evolution of electronic gadgets such as smartphones, tablets, and flat televisions that use back-lighted technology, such as compact fluorescent lamps (CFLs) and LEDs, exposes us to large amounts of harmful radiation. These devices emit HEBL and small amounts of UV. Natural blue light can regulate our sleep and wake cycles, boost alertness, modulate mood, etc., but prolonged exposure to blue light at night can disrupt circadian rhythm, and can cause many additional health issues, such as diabetes, heart disease, and depression. Most importantly it can cause permanent eye damage and age-related macular degradation, leading to vision loss. It is essential to block all UV and HEBL light with tunable filters having high visible light transparency to protect our health from these hazardous light sources. Carbon dots (CDs) are a newly discovered class of carbon-based nanomaterials that are composed only of earth-abundant, light elements such as carbon, oxygen, hydrogen, and nitrogen, which are non-toxic and completely metal-free. By utilizing the absorption and emission properties of CDs, we have developed a new hybrid film composed of carbon dots (CDs) and cellulose film combined via H-bonding. CDs encapsulated cellulose films (CDs@Cel) are highly transparent in the visible spectral region. These films efficiently absorb UV light and HEBL, simultaneously down-converting them to longer wavelengths in the visible spectrum.
References
1. Luther, U.; Dichmann, S.; Schlobe, A.; Czech, W.; Norgauer, J., UV light and skin cancer. Med Monatsschr Pharm 2000, 23 (8), 261-6.
2. Johnson, J. A., Durable protection against long-wavelength UV-A radiation and blue light. Arch Dermatol 1992, 128 (3), 409.
3. Barman. K, B.; Nagao, T.; Nanda, K. K., Dual roles of a transparent polymer film containing dispersed N-doped carbon dots: A high-efficiency blue light converter and UV screen. Applied Surface Science 2020, 510, 145405.

Biodegradable devices represent a new type of electronics that is built on fully biodegradable materials and is capable of degrading in aqueous environments, which can therefore eliminate a second surgery for device retraction and minimize environmental footprints. Such devices could play important roles in many therapeutic and diagnostic processes, as well as handling electronic waste. Herein, we introduce novel materials strategies and fabrication schemes that enable fully transient batteries based on magnesium anodes that can provide energy supplies for consumer electronics and implantable devices. The battery systems can offer sufficient energy density and prolonged operational lifetime. Self-powered nerve conduit for peripheral nerve regeneration based on biodegradable galvanic cells are also achieved. Successful nerve regrowth and motor functional recovery are realized in rodent models. These works provide new insights for building energy devices for green electronics and implantable electronic medicine.

Transient/degradable technology is a flourishing research area aimed at designing materials, devices, or systems that undergo controlled degradation processes after a period of stable and reliable operation. Transient devices work exactly like their conventional analogs but have an extra advantage; these devices can disintegrate into the environment in a controlled fashion without leaving any toxic products behind. Transient technology is rapidly gaining ground for biomedical applications, zero waste electronics, and data-secure hardware, to name a few. To power such devices, transient batteries are required. To date, there are very few reports on transient batteries in literature, mainly due to the lack of suitable soluble materials, fabrication schemes, and battery designs that must fulfill entirely different requirements than traditional batteries.
Here, we reported the development of a fully transient lithium-ion battery (LIB) with competitive electrochemical performance. At first, we designed a degradable separator based on polyvinyl alcohol and cellulose nanocrystals that offer several unique advantages: electrolyte (organic solvent-based) uptake up to 510%, the ionic conductivity of 3.077 mS/cm, electrochemical stability up to 5.5 V vs. Li/Li⁺, and a high transference number of 0.56. As a result, a stable lithium metal deposition and a high specific capacity of 105 mAh/g in Li/LiFePO₄ cell for over 250 cycles were achieved for the separator soaked in organic electrolyte. The toxic organic electrolyte was replaced with a biodegradable ionic liquid, providing an ionic conductivity of 0.988 mS/cm and a specific capacity of 87 mAh/g in Li/LiFePO₄ cell. Finally, the ionic liquid-separator pair was assembled into a fully transient lithium-vanadium(V) oxide (Li-V₂O₅) cell, which can be cycled over 400 times and degraded in 15 minutes once an aqueous trigger was applied. This prototype of a transient LIB represents a proof of concept to develop innovative transient energy storage systems with a long lifecycle.

The NCM (LiNi_xCo_yMn_zO₂) Lithium-ion batteries (LIBs) is the most widely used Li-ion batteries in commercial applications, due to its mature technique, medium cost, and excellent balance between stability and energy density. However, because of low cobalt contents, NCM type Li-ion batteries have less recyclable value than the conventional LCO (LiCoO₂) type, so that how to make effective recycling process becomes the top priority to increase the collection rate of spent NCM batteries.
In this work, a proposed process utilizes a combination of pyrometallurgical & physical separation to recovery cobalt, nickel, manganese, lithium from the cathode, and sorting copper, stainless steel from anode and battery cover.
It was found that cathode elements were reduced in the low-temperature zone (450-600 ^oC), furthermore, reduced metal shows lower impurity level in the following separating and leaching sections. As a whole, the recycling rate can be enhanced to 88 %, the recycling rate of cathode Co, Ni, and Mn are 99.5, 98.1, and 99.5 %, respectively, where the impurity aluminum in the product can be controlled to lower than 0.5 wt%, This proposed recycling process provides an effective process to recycle spent NCM LIBs.

The rapid growth of population generates huge waste, and its management is extremely challenging. In fact, wastewater is a well-recognized valuable source of renewable resources like water, energy, nutrients, heavy metals, etc. Considering the overall depletion of renewable resources from the earth, wastewater treatment facilities need to be upgraded as renewable resource recovery facilities. Such advancement replaces the use of fossil fuels for energy source and facilitates clean water production and cradle-to-cradle waste management. In this context, the bioelectrochemical system (BES) has gained much attention as it converts organics in wastewater to electrical energy by microbial interactions on the electrode. Beyond pollutant removal, BES exhibits critical functions like recovery of water, nutrients, and heavy metals from wastewater/industrial effluents. In recent years, extensive studies on BES have grown up with more research articles from different countries making this technology truly comprehensive.

The present talk will throw light into the various applications of BES, especially energy production from organic wastewater, concentrating nutrients and recovering water from urine, water recovery by desalination, and chromium and copper recovery from industrial effluents. The presentation will also brief on the prospects of recycling/reusing e-waste for synchronized removal/recovery of heavy metals along with energy production using BES.

Circular economy and the role of life-cycle analysis in the design and manufacturing of small electronic devices is the focus of this presentation. The transition towards a carbon neutral and circular economy as well as sustainability in the manufacturing of small electronic devices may be necessary and possible sooner that one could expect. There are enormous prospects in the recovery of valuable components and critical materials from e-waste as well as the promotion of eco-design and design for recyclability, all of which could be coupled with the business opportunities. According to some, if the circular economy were to be carried out extensively, it could reduce the consumption of new materials substantially - possibly by more than 50% by 2050. There are many barriers to moving from our currently-practiced cradle-to-grave economy, discussed in this presentation in the context of electrical and electronic equipment (EEE) devices as well as material design and development. This presentation provides perspective on recycling, life cycle analysis in the design process, challenges for e-waste recycling, and drivers for change in the complex industrial system.

Today it becomes more and more apparent that the conception of the Internet of Things (IOT) in the manner of objects equipped with a multitude of electronic sensors that all communicate with one another will pose serious problems both from ecological (energy consumption, e-waste) and technical (bandwidth limitations) point of views.
Nowadays, with the rise of light-emitting diode (LED) based luminaires also functionalities beyond illumination become more and more of relevance. For example, light can take over communication tasks and thereby offload the RF-spectrum. In this so-called visible light communication (VLC) scenario, the data are encoded into intensity modulations of the light emitted by the LEDs of the luminaires. Subsequently, these modulations are recorded by a photosensitive device, for example a photodiode. Furthermore, besides its application for communication, this infrastructure ((modulated) LEDs and photosensitive elements), can be also applied for another promising functionality future luminaires can provide, visible light positioning (VLP), which is on the way to play a decisive role in indoor localization.
While an enormous number of research studies focus on VLC and VLP, at present another potential functionality of artificial lighting, which again takes advantage of the same infrastructure as VLC and VLP, emerges: Visible Light Sensing (VLS). VLS expands the scope of functionalities of lighting into the domains of sensing and detection. In VLS, the photosensitive element records that light emitted from the luminaire that is reflected backwards from an object. Based on this principle and by equipping the objects with tailored reflective materials that purposively modulate the spectrum and/or the intensity of the light reflected from the object, information can be conveyed. Most notably, the basic concept of VLS only necessitates to equip the object with optical structures, but does not require any active device to be placed on the object. The basic conception of VLS relies on backscattering, which, in general, is one of the most promising technologies to be added in the 6G era of wireless communication technologies. Although most discussions on backscatter communication currently focus on RF-backscatter, similarly to the complementary role of VLC and RF for communication, also visible light-based backscatter technologies have a huge potential to complement RF-based ones.
An appropriate coding strategy for exploiting the visible light spectral range in this regard is to equip surfaces with colored “codes”, consisting of tailored sequences of different colors and the reflected light from this surface is detected with the help of an RGB-photodiode and further on analyzed. Appropriate machine learning algorithms can support this analysis and allow to maintain a high percentage of correct classifications even in case that the lighting conditions are changed.
Here we discuss appropriate system designs for artificial lighting sources, which allow for tunable artificial illumination (dimming and variation of color temperatures of the luminaires) while still being able to perform sensing tasks in parallel. Examples include the identification and velocity determination of indoor moving objects, the determination of the rotation direction and the rotation velocity of a robotic arm or the determination of the rotation of a human wrist by using a colored wristband. All these examples do not require any active devices to be placed on the objects. We show how the sensing tasks can be operated in parallel with tunable illumination and in parallel with communication (VLC). With this, artificial lighting, which is obligatory at least in indoor environments, including VLC, VLP and VLS functionalities turns out as a promising technology for fulfilling one of the crucial challenges of 6G, which is to amalgamate sensing, positioning and communication, while drastically reducing energy use and e-waste.

Cadmium-containing quantum dot nanoparticles (QDs) are integrated into electronic displays because of their ability to efficiently convert colors. There are conflicting accounts as to whether these particles present a hazard to the environment, as they have been studied either as (1) embedded QDs in display screen films or (2) as model QDs with small, hydrophilic ligands. Both approaches have limitations that we addressed by synthesizing QDs featuring the core-shell structure and the thick polymer coating present in commercial devices. These models are used to probe the effect of environmental fate, in the form of low pH conditions, aeroby and anaeroby, as well as their transformation. Toxicity with liver cells is analyzed for both pristine QDs and the ones exposed to different fate conditions. We also studied the fate of these model systems in gastrointestinal track (GIT) conditions and studied how each step leads to transformation of the QDs. GIT cells toxicity was also studied and cellular uptake explored.

Creating circular economies requires creating resilient, sustainable, and self-managing communities of people who see circularity as vital to their livelihoods. Dr. Elinor Ostrom (2009 Nobel Laureate in Economics) laid out a framework for how people and organizations are able to develop voluntary, community-based solutions involving adaptive, self-governing systems that effectively manage “the commons,” without the need for government regulations or privatization. I’ll present examples where this framework of viewing products as “commons” has been applied, including creating a circular economy for hard disk drives. We will discuss how these concepts can be applied not only to other systems, but also to create a university community to train students to view materials, components, and products as parts of potential circular economies.

The field of Green Electronics strives for the sustainable fabrication and utilization of electronics via responsible use of resources and elimination of negative environmental effects. The most direct way to mitigate negative sustainability issues in most end-of-life phases would be the utilization of inherently sustainable materials and processes from the very conception of a technology. this would effectively simplify or reduce the economic, energetic and environmental burden on regulation, recycling or recovery of electronic waste.

In this contribution, we will discuss our efforts towards the fabrication of ecofriendly organic electronic devices. We will present the investigation of biodegradable electrolyte systems based on gelatin, DNA, poly(lactic-co-glycolic acid) and Polycaprolactone for the fabrication of light-emitting electrochemical cells (LEC) and electrochromic (EC) devices. We will present inkjet-printed LECs exhibiting maximum luminance over 12,000 Cd/m² operational lifetimes > 100 h and emission covering all the visible spectrumwhich while containing > 90% ecofriendly materials. Furthermore, we will show EC devices which biodegradation was certified via an independently performed ISO (14855) test. These devices were integrated into a flexible inkjet-printed display demonstrating the potential of the industrial relevant printing techniques for the up-scalable fabrication of solution-processed ecofriendly electronics.

Sulfur-containing polymers have attracted increasing attention, owing to their fascinating properties such as metal coordination ability, high refractive indices, self-healing capability, optoelectronic property, and so on. However, the rapid development of sulfur-containing polymer materials are hindered by the lack of economic monomers and efficient synthetic approaches. On the other hand, the utilization of elemental sulfur is a global concern considering its large surplus from petroluem industry and the safety/environmental problems caused during its storage, which is an idea source for the preparation of sulfur-containing polymers with the challenges of the poor solubility of sulfur in organic solvents and its toxicity to transition metal catalysts.
In this talk, a series of elemental sulfur-based multicomponent polymerizations (MCPs) will be introduced to directly convert elemental sulfur to sulfur-containing polymers such as polythioamides, polythioureas, polycarbamothioates, and polythiophenes with well-defined structures, good solubility, high yields, and high molecular weights in one step. These MCPs can generally proceed smoothly with catalyst-free condition, at mild temperature such as room temperature, in air atmosphere, which also usually enjoy high atom economy and wide monomer scope, enabling facile construction of sulfur-containing polymer with great structural diversity. With the cost-effective monomers, mild conditions, and no harmful smelly side product released, several MCPs are proved to be scalable.
Besides the high refractive indices, potential high dielectric constants and semiconducting property for the potential application in sustainable electronics, these sulfur-containing polymers can also be applied in gold recovery from the abundantly discarded electronic wastes. They can extract trace amount of Au³⁺ selectively, rapidly, and efficiently from aqueous solution in the practical condition with strong acidity and other metal ion interferences, directly affording elemental gold with high purity through in situ reduction or simple pyrolysis.
These sulfur-based MCPs are economic, efficient, and convenient tools for the direct conversion from sulfur at mild condition to profitable sulfur-containing functional polymers, which could make use of both abundantly existing sulfur waste and trace amount of gold residue in electronic wastes, and accelerate the development of sulfur-containing polymers with diversified structures and functionalities, demonstrating their great potential in resource utilization and sustainable electronics.

Leveraging the biocatalytic machinery of living organisms for fabricating functional bioelectronic interfaces in-vivo not only enables seamless integration of microdevices into the tissue but also a greener solution for advanced microfabrication. Previously we have demonstrated that plants can polymerize conjugated oligomers in-vivo forming conductors within their structure. We showed that the polymerization is enzymatically catalyzed by endogenous peroxidases and we developed a series of conjugated oligomers that can be enzymatically polymerized in physiological conditions. The conjugated polymers integrate within the plant cell wall structure adding electronic functionality into the plant that is then explored for energy storage. Recently we have extended this concept into an animal model system. We demonstrate that Hydra, an invertebrate animal can polymerize intracellularly conjugated oligomers in cells that expresses peroxidase activity. The conjugated polymer forms electronically conducting and electrochemically active domains in the µm range integrated within the hydra tissue. Our work paves the way for self-organized electronics in plant and animal tissue for modulating biological functions and in-vivo bio-fabrication of hybrid functional materials and devices.

Next generation semiconductors such as the perovskites and organics can be sourced from earth abundant elements and processed from solution or via low temperature vapour deposition. This means they have intrinsically low embodied manufacturing energy and much reduced environmental footprints relative to more traditional semiconductor systems. In addition, organic semiconductors in particular (and in a more limited sense the perovskites) can be tuned at the molecular level to provide a vast palette of different materials with engineered electro-optical properties such as optical gap, absorption coefficient, electron affinity and ionization potential, etc. These ‘unique selling points’ are increasingly recognized as essentials for creating more sustainable electronic and optoelectronic technologies, including in areas such as the internet of things (power sources and sensors), wearable and bioelectronic healthcare, and mobile, local clean energy generation.
In my talk I will specifically focus on the development of bespoke, spectrally tuned photovoltaics and photodetector systems. I will discuss the latest advances in perovskite and organic semiconductor PV in relation to (for example) indoor local power generation including considerations such as materials design, thermodynamics, spectral matching and the constraints of the crucial transparent conductive electrode. I will also outline recent results and latest thinking on the development of organic and perovskite semiconductor photodetectors – both greyscale and color sensitive, and show how it may be possible to engineer so called ‘illuminant independent’ full color imaging photodetectors of the sort required for true machine / artificial vision.

Through its appealing avenues of processing the component devices at room temperature and from low-cost precursor materials, organic electronics has a tremendous potential for the development of products able to achieve the goals of production sustainability as well as environmental and human friendliness for electronics. In an effort to stave off the e-waste growth, the presenter and his research group went further down the path opened by organic electronics research and investigated a large number of biomaterials as substrates, dielectrics, semiconductors and smoothening layers for the fabrication of organic field effect transistors, integrated circuits and organic solar cells. The seminar presentation will focus on the highlights of our recent research, especially with respect to materials investigated, devices fabricated and the immense potential for follow up research:
-Flexible natural and biodegradable substrates with high resistance to solvent exposure and temperature stability
-Natural dielectrics
-Bio-origin, H-bonded semiconductors in the families of indigos, anthraquinones and acridones
-Bio-degradation protocols for organic semiconductors
The potential of follow-up research in the bioelectronics field is immense, with large area electronics fabrication, biomedical implants, bio-sensing and smart labeling, representing only the tip of the iceberg of many more immediate possibilities of high interest for our group. Natural and nature-inspired materials have the unrivalled capability to create “safe-first” electronic markets for human and environment, with minimal or even neutral carbon footprint.